Xenix System V

Xenix is a discontinued version of the Unix operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation in the late 1970s. The Santa Cruz Operation (SCO) later acquired exclusive rights to the software, and eventually replaced it with SCO UNIX (now known as SCO OpenServer).

In the mid-to-late 1980s, Xenix was the most common Unix variant, measured according to the number of machines on which it was installed.
Microsoft chairman Bill Gates said at Unix Expo in 1996 that, for a long time, Microsoft had the highest-volume AT&T Unix license.

History

Bell Labs, the developer of Unix, was part of the regulated Bell System and could not sell Unix directly to most end users (academic and research institutions excepted); it could, however, license it to software vendors who would then resell it to end users (or their own resellers), combined with their own added features. Microsoft, which expected that Unix would be its operating system of the future when personal computers became powerful enough, purchased a license for Version 7 Unix from AT&T in 1978, and announced on August 25, 1980, that it would make the software available for the 16-bit microcomputer market. Because Microsoft was not able to license the "Unix" name itself, the company gave it an original name.

Microsoft called Xenix "a universal operating environment". It did not sell Xenix directly to end users, but licensed the software to OEMs such as IBM, Intel, Management Systems Development, Tandy, Altos Computer, SCO, and Siemens (SINIX